The Spiritweb is a rather mysterious concept in the cosmere, very little is known about it for sure. However, it does seem likely that the Spiritweb is a person's Spiritual aspect. Evidence suggests that the Spiritweb is laid out in a specific pattern in a person. This pattern forms a network of lines and points.[2] These points are sort of Spiritual pressure points

The Spiritweb is related to "Spiritual DNA;" a person's Spiritual heritage from living on a specific Shardworld.[3] It is also passed down like regular DNA, from parents to children.[4] The Spiritweb is also implied to determine which manifestations of Investiture a person can utilize.[5][4]

Some manifestations of Investiture seem to be built into a person's Spiritual DNA, like Allomancy and Feruchemy. Other times, such as in Hemalurgy and potentially Surgebinding, involve manipulating Spiritual DNA. In Hemalurgy, portions of the Spiritweb seem to be ripped off of one person and grafted onto another person's Spiritweb.[2] A Surgebinder's Nahel bond with a spren may work in a similar way, a spren becoming spiritually attached to a certain point on a person's Spiritweb, sort of like a non-invasive form of Hemalurgy. AonDor requires some innate Spiritual DNA, but the change that turns someone into an Elantrian likely involves some sort of change to the Spiritual DNA during the Shaod. The ability to give Breath, which seems to be a part of a person's Spiritual aspect, appears to be built into a Nalthian's Spritual DNA. As a Shardblade can be stolen with Hemalurgy,[6] it seems likely that it is attached to a point in a person's Spiritweb as well.